| 1 | //! Diagnostic rendering: file:line:col header + source line + caret, |
| 2 | //! optionally colorised when stderr is a TTY. |
| 3 | //! |
| 4 | //! Sprint 32 #5 / #506. Output format mirrors gfortran / clang so |
| 5 | //! editors and IDEs can parse it with their existing regexes. |
| 6 | |
| 7 | use std::io::IsTerminal; |
| 8 | |
| 9 | use crate::lexer::Span; |
| 10 | |
| 11 | /// Severity of a rendered diagnostic. |
| 12 | #[derive(Debug, Clone, Copy, PartialEq, Eq)] |
| 13 | pub enum Level { |
| 14 | Error, |
| 15 | Warning, |
| 16 | Note, |
| 17 | } |
| 18 | |
| 19 | impl Level { |
| 20 | fn label(self) -> &'static str { |
| 21 | match self { |
| 22 | Level::Error => "error", |
| 23 | Level::Warning => "warning", |
| 24 | Level::Note => "note", |
| 25 | } |
| 26 | } |
| 27 | fn color(self) -> &'static str { |
| 28 | // ANSI SGR colour codes; matched to clang's defaults. |
| 29 | match self { |
| 30 | Level::Error => "\x1b[31;1m", // bright red |
| 31 | Level::Warning => "\x1b[33;1m", // bright yellow |
| 32 | Level::Note => "\x1b[34;1m", // bright blue |
| 33 | } |
| 34 | } |
| 35 | } |
| 36 | |
| 37 | /// True when the given fd looks like a TTY and ANSI escapes are |
| 38 | /// safe to emit. Honours NO_COLOR and CLICOLOR_FORCE per the |
| 39 | /// no-color.org convention so users / CI can override. |
| 40 | fn use_color() -> bool { |
| 41 | if std::env::var_os("NO_COLOR").is_some() { |
| 42 | return false; |
| 43 | } |
| 44 | if std::env::var_os("CLICOLOR_FORCE") |
| 45 | .map(|v| v != "0") |
| 46 | .unwrap_or(false) |
| 47 | { |
| 48 | return true; |
| 49 | } |
| 50 | std::io::stderr().is_terminal() |
| 51 | } |
| 52 | |
| 53 | const ANSI_RESET: &str = "\x1b[0m"; |
| 54 | const ANSI_BOLD: &str = "\x1b[1m"; |
| 55 | |
| 56 | /// Render a single diagnostic to stderr, gfortran-style: |
| 57 | /// file:line:col: error: message |
| 58 | /// 12 | print *, xyz |
| 59 | /// | ^^^ |
| 60 | /// |
| 61 | /// `source` is the full original source text — needed to extract the |
| 62 | /// line for the gutter view. `span_len` controls how wide the caret |
| 63 | /// underline is (defaults to a single `^` when zero). |
| 64 | pub fn render(file: &str, source: &str, span: Span, level: Level, message: &str, span_len: usize) { |
| 65 | let color = use_color(); |
| 66 | let (col_start, reset) = if color { |
| 67 | (level.color(), ANSI_RESET) |
| 68 | } else { |
| 69 | ("", "") |
| 70 | }; |
| 71 | let bold = if color { ANSI_BOLD } else { "" }; |
| 72 | |
| 73 | eprintln!( |
| 74 | "{bold}{file}:{line}:{col}:{reset} {col_start}{label}:{reset} {bold}{msg}{reset}", |
| 75 | bold = bold, |
| 76 | file = file, |
| 77 | line = span.start.line, |
| 78 | col = span.start.col, |
| 79 | reset = reset, |
| 80 | col_start = col_start, |
| 81 | label = level.label(), |
| 82 | msg = message, |
| 83 | ); |
| 84 | |
| 85 | if let Some((gutter, line_text, caret_indent, caret_len)) = snippet_for(source, span, span_len) |
| 86 | { |
| 87 | let blue = if color { "\x1b[34m" } else { "" }; |
| 88 | let gutter_width = gutter.to_string().len().max(5); |
| 89 | let caret_gutter = " ".repeat(gutter_width); |
| 90 | eprintln!( |
| 91 | "{blue}{gutter:>width$} |{reset} {line}", |
| 92 | gutter = gutter, |
| 93 | width = gutter_width, |
| 94 | reset = reset, |
| 95 | blue = blue, |
| 96 | line = line_text |
| 97 | ); |
| 98 | let mut caret = String::new(); |
| 99 | for _ in 0..caret_indent { |
| 100 | caret.push(' '); |
| 101 | } |
| 102 | for _ in 0..caret_len.max(1) { |
| 103 | caret.push('^'); |
| 104 | } |
| 105 | eprintln!( |
| 106 | "{blue}{caret_gutter} |{reset} {col_start}{caret}{reset}", |
| 107 | blue = blue, |
| 108 | caret_gutter = caret_gutter, |
| 109 | reset = reset, |
| 110 | col_start = col_start, |
| 111 | caret = caret |
| 112 | ); |
| 113 | } |
| 114 | } |
| 115 | |
| 116 | /// Pull the requested source line out of `source` for display. |
| 117 | /// Returns `(line_number, line_text, caret_indent, caret_len)`. |
| 118 | /// caret_indent is in display columns assuming a tab is replaced by |
| 119 | /// 4 spaces, matching how the line_text is emitted. |
| 120 | fn snippet_for(source: &str, span: Span, span_len: usize) -> Option<(u32, String, usize, usize)> { |
| 121 | if span.start.line == 0 { |
| 122 | return None; |
| 123 | } |
| 124 | let target = span.start.line as usize; |
| 125 | let raw_line = source.lines().nth(target.saturating_sub(1))?; |
| 126 | let display_line: String = raw_line.replace('\t', " "); |
| 127 | // span.start.col is 1-based. Convert tabs in the prefix to the |
| 128 | // same 4-space expansion so the caret lines up. |
| 129 | let prefix_chars = span.start.col.saturating_sub(1) as usize; |
| 130 | let mut indent = 0usize; |
| 131 | for (i, ch) in raw_line.chars().enumerate() { |
| 132 | if i >= prefix_chars { |
| 133 | break; |
| 134 | } |
| 135 | indent += if ch == '\t' { 4 } else { 1 }; |
| 136 | } |
| 137 | let caret_len = if span_len == 0 { 1 } else { span_len }; |
| 138 | Some((span.start.line, display_line, indent, caret_len)) |
| 139 | } |
| 140 |